1. Field of the invention
The present invention relates to a parts mounting apparatus. More specifically, the present invention relates to an apparatus for mounting small electronic parts such as a chip capacitor and chip resistor onto a printed circuit board through a series of work stations which are arranged in a closed-loop fashion at a periphery of a rotary-index table.
2. Description of the prior art
In the aforementioned apparatus, generally, a picking and placing operation of the parts is performed by a vacuum suction device. Recently, the variety of such parts are becoming wider. Therefore, a large variety of parts must be handled by a single mounting apparatus as much as possible. For this purpose, suction pieces having various shapes must be provided on the single mounting apparatus so as to be suited to objects. Making the suction pieces removable from the vacuum suction device is considered to be a way to form a proper mating of suction piece and part. Such examples are shown in, for example, Japanese Patent Application Laid-Open No. 69992/1984 and Utility Model Application Laid-Open No. 47167/1987. However, generally speaking, such an apparatus is just a robot arm provided with the vacuum suction device having a tool exchanging function, and it is hard to say that they are suitable for use in mounting a large number of parts at high speed.
More specifically, in the conventional X-Y robot type parts mounting apparatus, the vacuum suction device is moved reciprocally between a parts supply device and a printed circuit board if the suction piece is not intended to be exchanged. When the suction piece is to be exchanged after mounting of the part, the vacuum suction device is moved to a side path other than the moving path between the printed circuit board and the parts supply device, and the suction piece is changed in the side path. Thus, in the case where the suction piece is to be changed in the X-Y robot type parts mounting apparatus, an operation cycle becomes redundant and an operation speed becomes slow in comparison with the case where no suction piece is to be changed. Therefore, until now, there was no approach to incorporate "suction piece exchanging operation" which necessitates such a redundant operation cycle into the rotary-index table type parts mounting apparatus designed so as to perform a high-speed operation.
Furthermore, in the conventional X-Y robot type parts mounting apparatus, the vacuum suction device can be relatively freely moved in a desired path; however, in the rotary-index table type parts mounting apparatus, the vacuum suction device can be moved in only the fixed moving path. Such a lack of freedom in movement of the vacuum suction device in the rotary-index table type parts mounting apparatus also prevented a tool exchange system of the X-Y robot type parts mounting apparatus from being combined with the rotary-index table type parts mounting apparatus.